import collections.abc as collections
import json
import os
import warnings
from pathlib import Path
from shutil import copytree
from typing import Any, Dict, List, Optional, Union

from huggingface_hub import ModelHubMixin, snapshot_download
from huggingface_hub.utils import (
    get_tf_version,
    is_graphviz_available,
    is_pydot_available,
    is_tf_available,
    yaml_dump,
)

from .constants import CONFIG_NAME
from .hf_api import HfApi
from .utils import SoftTemporaryDirectory, logging, validate_hf_hub_args


logger = logging.get_logger(__name__)

if is_tf_available():
    import tensorflow as tf  # type: ignore


def _flatten_dict(dictionary, parent_key=""):
    """Flatten a nested dictionary.
    Reference: https://stackoverflow.com/a/6027615/10319735

    Args:
        dictionary (`dict`):
            The nested dictionary to be flattened.
        parent_key (`str`):
            The parent key to be prefixed to the children keys.
            Necessary for recursing over the nested dictionary.

    Returns:
        The flattened dictionary.
    """
    items = []
    for key, value in dictionary.items():
        new_key = f"{parent_key}.{key}" if parent_key else key
        if isinstance(value, collections.MutableMapping):
            items.extend(
                _flatten_dict(
                    value,
                    new_key,
                ).items()
            )
        else:
            items.append((new_key, value))
    return dict(items)


def _create_hyperparameter_table(model):
    """Parse hyperparameter dictionary into a markdown table."""
    if model.optimizer is not None:
        optimizer_params = model.optimizer.get_config()
        # flatten the configuration
        optimizer_params = _flatten_dict(optimizer_params)
        optimizer_params["training_precision"] = tf.keras.mixed_precision.global_policy().name
        table = "| Hyperparameters | Value |\n| :-- | :-- |\n"
        for key, value in optimizer_params.items():
            table += f"| {key} | {value} |\n"
    else:
        table = None
    return table


def _plot_network(model, save_directory):
    tf.keras.utils.plot_model(
        model,
        to_file=f"{save_directory}/model.png",
        show_shapes=False,
        show_dtype=False,
        show_layer_names=True,
        rankdir="TB",
        expand_nested=False,
        dpi=96,
        layer_range=None,
    )


def _create_model_card(
    model,
    repo_dir: Path,
    plot_model: bool = True,
    metadata: Optional[dict] = None,
):
    """
    Creates a model card for the repository.

    Do not overwrite an existing README.md file.
    """
    readme_path = repo_dir / "README.md"
    if readme_path.exists():
        return

    hyperparameters = _create_hyperparameter_table(model)
    if plot_model and is_graphviz_available() and is_pydot_available():
        _plot_network(model, repo_dir)
    if metadata is None:
        metadata = {}
    metadata["library_name"] = "keras"
    model_card: str = "---\n"
    model_card += yaml_dump(metadata, default_flow_style=False)
    model_card += "---\n"
    model_card += "\n## Model description\n\nMore information needed\n"
    model_card += "\n## Intended uses & limitations\n\nMore information needed\n"
    model_card += "\n## Training and evaluation data\n\nMore information needed\n"
    if hyperparameters is not None:
        model_card += "\n## Training procedure\n"
        model_card += "\n### Training hyperparameters\n"
        model_card += "\nThe following hyperparameters were used during training:\n\n"
        model_card += hyperparameters
        model_card += "\n"
    if plot_model and os.path.exists(f"{repo_dir}/model.png"):
        model_card += "\n ## Model Plot\n"
        model_card += "\n<details>"
        model_card += "\n<summary>View Model Plot</summary>\n"
        path_to_plot = "./model.png"
        model_card += f"\n![Model Image]({path_to_plot})\n"
        model_card += "\n</details>"

    readme_path.write_text(model_card)


def save_pretrained_keras(
    model,
    save_directory: Union[str, Path],
    config: Optional[Dict[str, Any]] = None,
    include_optimizer: bool = False,
    plot_model: bool = True,
    tags: Optional[Union[list, str]] = None,
    **model_save_kwargs,
):
    """
    Saves a Keras model to save_directory in SavedModel format. Use this if
    you're using the Functional or Sequential APIs.

    Args:
        model (`Keras.Model`):
            The [Keras
            model](https://www.tensorflow.org/api_docs/python/tf/keras/Model)
            you'd like to save. The model must be compiled and built.
        save_directory (`str` or `Path`):
            Specify directory in which you want to save the Keras model.
        config (`dict`, *optional*):
            Configuration object to be saved alongside the model weights.
        include_optimizer(`bool`, *optional*, defaults to `False`):
            Whether or not to include optimizer in serialization.
        plot_model (`bool`, *optional*, defaults to `True`):
            Setting this to `True` will plot the model and put it in the model
            card. Requires graphviz and pydot to be installed.
        tags (Union[`str`,`list`], *optional*):
            List of tags that are related to model or string of a single tag. See example tags
            [here](https://github.com/huggingface/hub-docs/blob/main/modelcard.md?plain=1).
        model_save_kwargs(`dict`, *optional*):
            model_save_kwargs will be passed to
            [`tf.keras.models.save_model()`](https://www.tensorflow.org/api_docs/python/tf/keras/models/save_model).
    """
    if is_tf_available():
        import tensorflow as tf
    else:
        raise ImportError("Called a Tensorflow-specific function but could not import it.")

    if not model.built:
        raise ValueError("Model should be built before trying to save")

    save_directory = Path(save_directory)
    save_directory.mkdir(parents=True, exist_ok=True)

    # saving config
    if config:
        if not isinstance(config, dict):
            raise RuntimeError(f"Provided config to save_pretrained_keras should be a dict. Got: '{type(config)}'")

        with (save_directory / CONFIG_NAME).open("w") as f:
            json.dump(config, f)

    metadata = {}
    if isinstance(tags, list):
        metadata["tags"] = tags
    elif isinstance(tags, str):
        metadata["tags"] = [tags]

    task_name = model_save_kwargs.pop("task_name", None)
    if task_name is not None:
        warnings.warn(
            "`task_name` input argument is deprecated. Pass `tags` instead.",
            FutureWarning,
        )
        if "tags" in metadata:
            metadata["tags"].append(task_name)
        else:
            metadata["tags"] = [task_name]

    if model.history is not None:
        if model.history.history != {}:
            path = save_directory / "history.json"
            if path.exists():
                warnings.warn(
                    "`history.json` file already exists, it will be overwritten by the history of this version.",
                    UserWarning,
                )
            with path.open("w", encoding="utf-8") as f:
                json.dump(model.history.history, f, indent=2, sort_keys=True)

    _create_model_card(model, save_directory, plot_model, metadata)
    tf.keras.models.save_model(model, save_directory, include_optimizer=include_optimizer, **model_save_kwargs)


def from_pretrained_keras(*args, **kwargs) -> "KerasModelHubMixin":
    r"""
    Instantiate a pretrained Keras model from a pre-trained model from the Hub.
    The model is expected to be in `SavedModel` format.

    Args:
        pretrained_model_name_or_path (`str` or `os.PathLike`):
            Can be either:
                - A string, the `model id` of a pretrained model hosted inside a
                  model repo on huggingface.co. Valid model ids can be located
                  at the root-level, like `bert-base-uncased`, or namespaced
                  under a user or organization name, like
                  `dbmdz/bert-base-german-cased`.
                - You can add `revision` by appending `@` at the end of model_id
                  simply like this: `dbmdz/bert-base-german-cased@main` Revision
                  is the specific model version to use. It can be a branch name,
                  a tag name, or a commit id, since we use a git-based system
                  for storing models and other artifacts on huggingface.co, so
                  `revision` can be any identifier allowed by git.
                - A path to a `directory` containing model weights saved using
                  [`~transformers.PreTrainedModel.save_pretrained`], e.g.,
                  `./my_model_directory/`.
                - `None` if you are both providing the configuration and state
                  dictionary (resp. with keyword arguments `config` and
                  `state_dict`).
        force_download (`bool`, *optional*, defaults to `False`):
            Whether to force the (re-)download of the model weights and
            configuration files, overriding the cached versions if they exist.
        resume_download (`bool`, *optional*, defaults to `False`):
            Whether to delete incompletely received files. Will attempt to
            resume the download if such a file exists.
        proxies (`Dict[str, str]`, *optional*):
            A dictionary of proxy servers to use by protocol or endpoint, e.g.,
            `{'http': 'foo.bar:3128', 'http://hostname': 'foo.bar:4012'}`. The
            proxies are used on each request.
        token (`str` or `bool`, *optional*):
            The token to use as HTTP bearer authorization for remote files. If
            `True`, will use the token generated when running `transformers-cli
            login` (stored in `~/.huggingface`).
        cache_dir (`Union[str, os.PathLike]`, *optional*):
            Path to a directory in which a downloaded pretrained model
            configuration should be cached if the standard cache should not be
            used.
        local_files_only(`bool`, *optional*, defaults to `False`):
            Whether to only look at local files (i.e., do not try to download
            the model).
        model_kwargs (`Dict`, *optional*):
            model_kwargs will be passed to the model during initialization

    <Tip>

    Passing `token=True` is required when you want to use a private
    model.

    </Tip>
    """
    return KerasModelHubMixin.from_pretrained(*args, **kwargs)


@validate_hf_hub_args
def push_to_hub_keras(
    model,
    repo_id: str,
    *,
    config: Optional[dict] = None,
    commit_message: str = "Push Keras model using huggingface_hub.",
    private: bool = False,
    api_endpoint: Optional[str] = None,
    token: Optional[str] = None,
    branch: Optional[str] = None,
    create_pr: Optional[bool] = None,
    allow_patterns: Optional[Union[List[str], str]] = None,
    ignore_patterns: Optional[Union[List[str], str]] = None,
    delete_patterns: Optional[Union[List[str], str]] = None,
    log_dir: Optional[str] = None,
    include_optimizer: bool = False,
    tags: Optional[Union[list, str]] = None,
    plot_model: bool = True,
    **model_save_kwargs,
):
    """
    Upload model checkpoint to the Hub.

    Use `allow_patterns` and `ignore_patterns` to precisely filter which files should be pushed to the hub. Use
    `delete_patterns` to delete existing remote files in the same commit. See [`upload_folder`] reference for more
    details.

    Args:
        model (`Keras.Model`):
            The [Keras model](`https://www.tensorflow.org/api_docs/python/tf/keras/Model`) you'd like to push to the
            Hub. The model must be compiled and built.
        repo_id (`str`):
                ID of the repository to push to (example: `"username/my-model"`).
        commit_message (`str`, *optional*, defaults to "Add Keras model"):
            Message to commit while pushing.
        private (`bool`, *optional*, defaults to `False`):
            Whether the repository created should be private.
        api_endpoint (`str`, *optional*):
            The API endpoint to use when pushing the model to the hub.
        token (`str`, *optional*):
            The token to use as HTTP bearer authorization for remote files. If
            not set, will use the token set when logging in with
            `huggingface-cli login` (stored in `~/.huggingface`).
        branch (`str`, *optional*):
            The git branch on which to push the model. This defaults to
            the default branch as specified in your repository, which
            defaults to `"main"`.
        create_pr (`boolean`, *optional*):
            Whether or not to create a Pull Request from `branch` with that commit.
            Defaults to `False`.
        config (`dict`, *optional*):
            Configuration object to be saved alongside the model weights.
        allow_patterns (`List[str]` or `str`, *optional*):
            If provided, only files matching at least one pattern are pushed.
        ignore_patterns (`List[str]` or `str`, *optional*):
            If provided, files matching any of the patterns are not pushed.
        delete_patterns (`List[str]` or `str`, *optional*):
            If provided, remote files matching any of the patterns will be deleted from the repo.
        log_dir (`str`, *optional*):
            TensorBoard logging directory to be pushed. The Hub automatically
            hosts and displays a TensorBoard instance if log files are included
            in the repository.
        include_optimizer (`bool`, *optional*, defaults to `False`):
            Whether or not to include optimizer during serialization.
        tags (Union[`list`, `str`], *optional*):
            List of tags that are related to model or string of a single tag. See example tags
            [here](https://github.com/huggingface/hub-docs/blob/main/modelcard.md?plain=1).
        plot_model (`bool`, *optional*, defaults to `True`):
            Setting this to `True` will plot the model and put it in the model
            card. Requires graphviz and pydot to be installed.
        model_save_kwargs(`dict`, *optional*):
            model_save_kwargs will be passed to
            [`tf.keras.models.save_model()`](https://www.tensorflow.org/api_docs/python/tf/keras/models/save_model).

    Returns:
        The url of the commit of your model in the given repository.
    """
    api = HfApi(endpoint=api_endpoint)
    repo_id = api.create_repo(repo_id=repo_id, token=token, private=private, exist_ok=True).repo_id

    # Push the files to the repo in a single commit
    with SoftTemporaryDirectory() as tmp:
        saved_path = Path(tmp) / repo_id
        save_pretrained_keras(
            model,
            saved_path,
            config=config,
            include_optimizer=include_optimizer,
            tags=tags,
            plot_model=plot_model,
            **model_save_kwargs,
        )

        # If `log_dir` provided, delete remote logs and upload new ones
        if log_dir is not None:
            delete_patterns = (
                []
                if delete_patterns is None
                else (
                    [delete_patterns]  # convert `delete_patterns` to a list
                    if isinstance(delete_patterns, str)
                    else delete_patterns
                )
            )
            delete_patterns.append("logs/*")
            copytree(log_dir, saved_path / "logs")

        return api.upload_folder(
            repo_type="model",
            repo_id=repo_id,
            folder_path=saved_path,
            commit_message=commit_message,
            token=token,
            revision=branch,
            create_pr=create_pr,
            allow_patterns=allow_patterns,
            ignore_patterns=ignore_patterns,
            delete_patterns=delete_patterns,
        )


class KerasModelHubMixin(ModelHubMixin):
    """
    Implementation of [`ModelHubMixin`] to provide model Hub upload/download
    capabilities to Keras models.


    ```python
    >>> import tensorflow as tf
    >>> from huggingface_hub import KerasModelHubMixin


    >>> class MyModel(tf.keras.Model, KerasModelHubMixin):
    ...     def __init__(self, **kwargs):
    ...         super().__init__()
    ...         self.config = kwargs.pop("config", None)
    ...         self.dummy_inputs = ...
    ...         self.layer = ...

    ...     def call(self, *args):
    ...         return ...


    >>> # Initialize and compile the model as you normally would
    >>> model = MyModel()
    >>> model.compile(...)
    >>> # Build the graph by training it or passing dummy inputs
    >>> _ = model(model.dummy_inputs)
    >>> # Save model weights to local directory
    >>> model.save_pretrained("my-awesome-model")
    >>> # Push model weights to the Hub
    >>> model.push_to_hub("my-awesome-model")
    >>> # Download and initialize weights from the Hub
    >>> model = MyModel.from_pretrained("username/super-cool-model")
    ```
    """

    def _save_pretrained(self, save_directory):
        save_pretrained_keras(self, save_directory)

    @classmethod
    def _from_pretrained(
        cls,
        model_id,
        revision,
        cache_dir,
        force_download,
        proxies,
        resume_download,
        local_files_only,
        token,
        **model_kwargs,
    ):
        """Here we just call [`from_pretrained_keras`] function so both the mixin and
        functional APIs stay in sync.

                TODO - Some args above aren't used since we are calling
                snapshot_download instead of hf_hub_download.
        """
        if is_tf_available():
            import tensorflow as tf
        else:
            raise ImportError("Called a TensorFlow-specific function but could not import it.")

        # TODO - Figure out what to do about these config values. Config is not going to be needed to load model
        cfg = model_kwargs.pop("config", None)

        # Root is either a local filepath matching model_id or a cached snapshot
        if not os.path.isdir(model_id):
            storage_folder = snapshot_download(
                repo_id=model_id,
                revision=revision,
                cache_dir=cache_dir,
                library_name="keras",
                library_version=get_tf_version(),
            )
        else:
            storage_folder = model_id

        model = tf.keras.models.load_model(storage_folder, **model_kwargs)

        # For now, we add a new attribute, config, to store the config loaded from the hub/a local dir.
        model.config = cfg

        return model
